Effects of Parafossarulus striatulus on the Growth of Vallisneria spiralis Relationship between Periphyton Distribution and Water Quality of Gufu River of Three Gorges Reservoir Area Response of periphyton to nutrient level and relationships between periphyton and decay degree of Potamogeton crispus Increased Benthic Algal Primary Production in Response to the Invasive Zebra Mussel (Dreissena polymorpha) in a Productive Ecosystem, Oneida Lake, NY Characteristerics of periphyton community in the source of Fenhe River, North China